ISTANBUL The US Federal Reserve chair has hit back at allegations of wrongdoing in renovations to the central bank’s Washington headquarters, saying changes to the 1930s-era buildings were badly needed, duly approved, and transparent. In a late Thursday letter to White House Office of Management and Budget head Russell Vought, Jerome Powell said information on the project was added to the Fed's website as a matter of transparency, and that this information supported his June 25 appearance